[Parse] Disable support for multiline/extended escaping string literal

in attribute message

Strings of diagnostics message processed in EncodedDiagnosticMessage
aren't necessarily from parsed Swift source code. That means, they might
not have quotes around it. Furthermore, memory around them might not be
managed. The logic in 'Lexer::getEncodedStringSegment()' used to cause
access violation.

For now, disable multiline string literal and extended escaping in string
literal for attribute message position. Considering the message might be
from Clang, we cannot simply enable this.

rdar://problem/44228891

Author: rintaro

include/swift/AST/DiagnosticsParse.def

@@ -1295,7 +1295,11 @@ ERROR(swift_native_objc_runtime_base_must_be_identifier,none,
       "@_swift_native_objc_runtime_base class name must be an identifier", ())
 
 ERROR(attr_interpolated_string,none,
-"%0 cannot be an interpolated string literal", (StringRef))
+"'%0' cannot be an interpolated string literal", (StringRef))
+ERROR(attr_multiline_string,none,
+"'%0' cannot be a multiline string literal", (StringRef))
+ERROR(attr_extended_escaping_string,none,
+"'%0' cannot be an extended escaping string literal", (StringRef))
 
 ERROR(attr_only_at_non_local_scope, none,
       "attribute '%0' can only be used in a non-local scope", (StringRef))

lib/Parse/Lexer.cpp

@@ -2108,26 +2108,6 @@ StringRef Lexer::getEncodedStringSegment(StringRef Bytes,
   // range check subscripting on the StringRef.
   const char *BytesPtr = Bytes.begin();
 
-  // Special case when being called from EncodedDiagnosticMessage(...).
-  // This allows multiline and delimited strings to work in attributes.
-  // The string has already been validated by the initial parse.
-  if (IndentToStrip == ~0u && CustomDelimiterLen == ~0u) {
-    IndentToStrip = CustomDelimiterLen = 0;
-
-    // Restore trailing indent removal for multiline.
-    const char *Backtrack = BytesPtr - 1;
-    if (Backtrack[-1] == '"' && Backtrack[-2] == '"') {
-      Backtrack -= 2;
-      for (const char *Trailing = Bytes.end() - 1;
-           *Trailing == ' ' || *Trailing == '\t'; Trailing--)
-        IndentToStrip++;
-    }
-
-    // Restore delimiter if any.
-    while (*--Backtrack == '#')
-      CustomDelimiterLen++;
-  }
-
   bool IsEscapedNewline = false;
   while (BytesPtr < Bytes.end()) {
     char CurChar = *BytesPtr++;

lib/Parse/ParseDecl.cpp

@@ -300,6 +300,16 @@ bool Parser::parseTopLevel() {
 static Optional<StringRef>
 getStringLiteralIfNotInterpolated(Parser &P, SourceLoc Loc, const Token &Tok,
                                   StringRef DiagText) {
+  // FIXME: Support extended escaping / multiline string literal.
+  if (Tok.getCustomDelimiterLen()) {
+    P.diagnose(Loc, diag::attr_extended_escaping_string, DiagText);
+    return None;
+  }
+  if (Tok.isMultilineString()) {
+    P.diagnose(Loc, diag::attr_multiline_string, DiagText);
+    return None;
+  }
+
   SmallVector<Lexer::StringSegment, 1> Segments;
   P.L->getStringLiteralSegments(Tok, Segments);
   if (Segments.size() != 1 ||

lib/Sema/TypeChecker.h

@@ -2164,7 +2164,7 @@ class EncodedDiagnosticMessage {
 public:
   /// \param S A string with an encoded message
   EncodedDiagnosticMessage(StringRef S)
-      : Message(Lexer::getEncodedStringSegment(S, Buf, true, true, ~0, ~0)) {}
+      : Message(Lexer::getEncodedStringSegment(S, Buf)) {}
 
   /// The unescaped message to display to the user.
   const StringRef Message;

test/Parse/diagnose_availability.swift

@@ -62,3 +62,22 @@ func swiftDeprecatedObsoleted() {}
 // expected-warning@-1 {{expected 'introduced', 'deprecated', or 'obsoleted' in 'available' attribute for platform 'swift'}}
 func swiftMessage() {}
 
+@available(*, unavailable, message: "\("message")")
+// expected-error@-1{{'message' cannot be an interpolated string literal}}
+func interpolatedMessage() {}
+
+// expected-error@+1{{'message' cannot be a multiline string literal}}
+@available(*, unavailable, message: """
+  foobar message.
+  """)
+func multilineMessage() {}
+
+// expected-error@+1{{'message' cannot be an extended escaping string literal}}
+@available(*, unavailable, message: #"""
+  foobar message.
+  """#)
+func extendedEscapedMultilineMessage() {}
+
+// expected-error@+1{{'renamed' cannot be an extended escaping string literal}}
+@available(*, unavailable, renamed: #"avialable()"#)
+func extenedEscpaedRenamed() {}